Characteristics of spin-valve films with non-magnetic oxide layers for specular-scattering

We found a new spin-valve structure in which low coercivity coexists with high GMR ratio is substrate/Ta/NiFe/PtMn/CoFe/Ru/Ox/CoFe/Cu/CoFe/Cu/Ta-O. “Ox” means that Ru layer surface was exposed to oxygen gas. In this structure, the free layer is separated from the top specular layer by a copper layer and shows no increase in coercivity. Furthermore, the free layer was well oriented due to the thin oxide layer in the bottom pinned layer and the coercivity did not increase. After annealing at 295°C, GMR and the exchange-bias field showed little change, which meant the oxide layers were stable. For the structure glass/Ta [3 nm]/NiFe [2 nm]/PtMn [10 nm]/CoFe [1.5 nm]/Ru [0.8 nm]/Ox/CoFe [2 nm]/Cu [2 nm]/CoFe [2 nm]/Cu [1 nm]Ta-O [1 nm], GMR ratio of 14.9% and change in sheet resistance of 3.3 ohms were obtained. The coercivity of the free layer exhibited 0.4 Oe